This invention relates generally to an electrical control apparatus, and more specifically to an electrical control apparatus for controlling both the amperage and polarity of electric current as may be used, for example, in welding apparatus, and more particularly in connection with multi-operator welding systems.
Dual polarity welding control systems are known in the prior art. One such system, sold under the trademark SUPER GOLIATH by Neoweld Corporation, includes a handle extending out through the front panel to permit reversal of polarity, as needed or desired.
Unfortunately, while a welding operation is being performed by a welding specialist his or her fellow employees may either playfully, or inadvertently switch the voltage polarity. In addition to upsetting the operator, this switching of polarity can burn out circuit components of the control system, thereby necessitating expensive repair or replacement of the device.
In multi-operator welding systems a number of control panels are mounted in a stationary frame member, to permit a number of operators to simultaneously perform welding operations. In some instances the maximum current output from a single control panel is not adequate to perform a required welding operation, thereby requiring that additional current somehow be introduced into the system. This often is required when welding under positive polarity conditions, but is not required when welding under negative potential conditions. A need is believed to exist for a simple, reliable system for permitting multiple, adjacent control panels to be electrically connected, or "ganged" together, when welding under positive polarity conditions, while preventing the shorting of the system when such adjacent control panels are being operated under different polarity conditions.
The following patents may be deemed relevant to the subject invention:
______________________________________ U.S. PAT. NOS. 814,332 3,573,561 950,107 3,610,850 2,218,555 3,626,253 2,353,518 3,703,621 2,762,015 3,800,103 2,762,878 3,823,288 2,767,266 3,903,384 2,980,824 3,914,659 3,247,445 3,957,333 3,274,356 4,020,301 3,295,025 4,184,191 3,316,452 4,204,243 3,343,042 4,317,160 3,440,371 4,482,936 3,452,211 4,531,174 4,563,549 FOREIGN PATENTS 205,981 Australia DE 3,013,517 Al Germany 54-109149 Japan ______________________________________